This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 'The ease with which we perform tasks in which the two hands execute quite different actions belies the fact that there is a strong tendency for the movements of the upper limbs to be drawn together. This research seeks to establish the cortical mechanisms which mediate bilateral interactions between the upper limbs and to elucidate the manner in which manipulations of task context give rise to changes in the functional contributions of these mechanisms. This strategic basic research, conducted with neurologically intact individuals, will advance our understanding of the bilateral organisation of descending motor pathways and will be of profound importance in designing strategies of motor rehabilitation for the upper limb.